Procedure and apparatus for controlling the treatment of flowing material



Jan. 6, 1942. D. CRAMPTON 2,269,393

PROCEDURE AND APPARATUS FOR CONTROLLING THE TREATMENT OF FLQWINGMATERIAL Filed April 7, 1939 4 Sheets-Sheet l INVENTOR nga/an ATTORNEYSJan. 6, 1942.

4 Sheets-Sheet 2 D. CRAMPTON PROCEDURE AND APPARATUS FOR CONTROLLING THEFiled April 7, 1939 TREATMENT OF FLOWING MATERIAL dub INVENTOR Jamil[ramp/01 BY -rrah I Kw ATTORNEYS,-

4 Sheets-Sheet 5 D. CRAMPTQN Filed April 7, 1 939 TREATMENT OF FLOWINGMATERIAL INVENTOR i M4 ATTQRNEY BY rr, Km

- PROCEDURE AND APPARATUS FOR CONTROLLING THE NNWEW Jan. 6, 1942.

Patented Jan. 6, 1942 PROCEDURE AND APPARATUS FOR CON- TROLLING THETREATMENT OF FLOWING MATERIAL David Crampton, Montclair, N. J., assignorto Wallace & Tiernan Co. Inc., Belleville, N. J., a

corporation of New York Application April 7, 1939, Serial No. 266,595

23 Claims.

This invention relates to procedure and apparatus for controlling thetreatment of flowing material, especially treatments such as the addi:-tion of chemicals or the like to a moving body of liquid, wherein theremay be variation both in the rate of flow, i. e. the quantity ofmaterial presented for treatment per unit of time, and in the demand ofthe material for treatment per unit quantity, e. g. the. amount oftreating substance needed per unit quantity to obtain a desired result.Accordingly an important object of the invention is to provide improvedcontrol procedure and systems which are adaptable to such conditions andwhich will afford a sensitive and accurate control of the treatment inproportion to both of the desired types of variation.

Another object of the invention is to provide for demand-proportionedcontrol with a minimum of hunting or fluctuation of response, incontrast to common types of control systems wherein the rate oftreatment is controlled by readings of the result of treatment after thelatter has been made. Although theoretically of an average accuracy,systems of the prior type just mentioned usually have a bad tendency tohunt, and indeed as a result of the hunting or of factors thatcontribute to hunting, a desirable accuracy of response is oftendiflicult or impossible to obtain. The present invention, however, isdesigned to provide both an improved accuracy of response andanavoidance of hunting, by methods and means which are advantageouslyadapted for continuous operation to obtain an accurately uniformtreatment of the material.

A further object of the invention is to provide new and improved methodsand apparatus for controlling the chlorination of aqueous liquids suchas sewage, water supplyor the like. For example, in sewage disposalplants chlorination is often desired, for one or more of severalreasons-as toprevent odor formations, or to reduce the bio-chemicaloxygen demand of the eflluent. Inpractice. chlorination for odor controlis frequently efiected by applying chlorine to the fluid entering theplant before the settling basins and filters, while for bio-chemicaloxygen demand reduction, chlorine is often applied just ahead of finalsettling.

In most sewage Plants, the flow is variable over f wide limits evenduring short periods of time, and

the variations in rate of flow are sometimes aggravated by theuse ofintermittent pumps. Furthermore, the chlorine demand per unit quantityof material often varies over wide limits,

and very rapidly, during both day and night operation; and this type ofvariation, as well as variation in rate of flow, may be experienced evenin the lar est plants where some mixing can occur prior to the arrivalof the material at the plant. Heretofore, control in accordance withrate of flow has been achieved by the use of flow-responsive devices,and it has also been sought to control the chlorination by takingreadings of the residual chlorine content of the sewage after theapplication of chlorine and after its intended reaction has beensubstantially completed. However, the time for such completion ofreaction is apt to be relatively long, and further time may also elapsein bringing thesampie to the measuring device in cases where continuousmeasuring apparatus is employed. This total period, principallyaccounted for by time of reaction, may be anywhere from 2 to 10 minutesor more, and thus'if the chlorination a controller is actuated by thedescribed measurement of the treated material, its control is alwaysfrom 2 to 10 minutes or more behind the actual changes in chlorinedemand which are presented at the point of chlorine application.

As a result the control is inaccurate and if it is possible to make abasic adjustment of the chlorination to maintain an excessive average ofresidual chlorine (so that the necessary results may be obtainedregardless of rapid variation in demand), there is a considerable wasteof chlorine; and in any event the system is apt to hunt badly. Thepresent invention, therefore, aims to provide control systems andprocedure for chlorination of sewage and other aqueous liquids, or forother application of treating material which requires a considerableperiod of time before detection of results is practicable, whereinaccuracy of response, avoidance of hunting and economy of the chlorineor other treating substance are achieved.

Other objects and advantages include those which are hereinafter statedor which are incidental to the use of the invention as hereinafterdescribed.

Certain presently preferred embodiments of the invention are shown, byway of example, in the accompanying drawings, wherein:

Fig. 1 is a' diagrammatic view of a control system for the applicationof chlorine in the treat-- ment of sewage or the like;

Fig. 2 is an enlarged diagrammatic view of certain parts of theapparatus shown in Fig. 1;

Fig. 3'is a diagrammatic view of a modification in certain portions ofthe apparatus of Fig. 1;

Fig. 4 is an elevational view in diagrammatic form, of a modified systemof the invention; and

Fig. 5 is a diagrammatic view showing certain further elements of thesystem of Fig. 4 and illustrating the features of Fig. 4 in plan view.

Referring first to Figs. 1 and 2, the invention is illustrated asapplied to a sewage plant, or portion thereof, wherein the sewage I0,industrial waste or like liquid to be'treated, enters the control andtreating zones in a conduit, e. g. an open channel I I, passes through ascreen I2, and

flows over a weir I3, into a further channel I4,

through which it flows, for example, to a primary settling basin I5. Thesettling basin, for instance, may be of the continuous type having slowmoving paddles I6, on a suitable conveyor, which push the settledmaterials to a sump II, where they may be dumped off for furthertreatment; and the resulting partially clarified liquid flows on throughan outlet channel I8. In the example illustrated chlorine is appliedthrough the pipe I9 which opens into the channel I4 at a point ahead ofthe primary settling basin; but it will be understood that in some caseschlorination of the flowing material may be affected at other pointsthan in a channel or pipe-e. g., at a The overflow box 26 thus maintainsa constant head for the liquid in it and from the bottom of the box 26,at the described constant head, a

small sample of the chlorine-treated liquid flows down through a pipe 29into a measuring cell 30 for detection of the residual chlorine content.

The cell 36 may conveniently be an electrolytic basin or tank into whichthe liquid is constantly To provide for control in accordance with rateof flow, a float 20 is disposed in the stream of sewage II) at the pointwhere it overflows the weir I3, and it will be readily appreciated thatthe upward force exerted by the float (which is restrained, by meanshereinafter explained, from appreciable movement) will vary in responseto variations in the rate of flow of the liquid, 1. e. its flow over theweir. In the illustrated system, the chlorinator controllingarrangements are such as to require that the variations of force exertedby the float be proportional tothe square of the rate of flow,- and suchcontrol may be obtained by utilizing a weir float 20 which is of specialconical configuration, thus cooperating, for the aforesaid purpose, withthe otherwise existing relation between flow and float displacing force,as will be understood by those skilled in the art.

An important feature of the invention is that the rate of chlorinationis controlled not only in accordance with variations in flow, but alsoin accordance with variations in chlorine demand of the liquid per unitquantity, as detected in the untreated liquid sampled from a pointupstream of the place of chlorine application. To that end, a pipe 2 I,having an outlet 22 into the stream of sewage ID as the latter passesalong the chanthough in some cases the apparatus can be operated with afixed flow of chlorine above or below the preferred adjustment justmentioned). The chlorine-treated sample then pass s through a furtherconduit 25 to an overflow box 26, which has a constant-level edge orweir 2'! over which excess liquid may flow and be returned to the mainstream through pipe 28.

device of the type shown and described in United States Patent No.2,076,964, issued April 13, 1937, to Richard Pomeroy for Process andapparatus for water purification; or, for instance, it may be or includea device of the types invented by Charles F. Wallace,-for example,electrical cell apparatus of types disclosed and claimed in hiscopending applications Serial Nos. 263,659 and 263,660, filed March 23,1939, for Fluid electrodes and for Cells and systems for use in thecontrol of compositions of fluids, respectively. It will be understoodthat-such devices afford a measurement of a potential which can becorrelated to the amount of residual chlorine in the treated liquid perunit quantity. It will be noted that the cell 30 is convenientlyprovided with a constant-level outlet pipe 3|, whereby a constant levelis maintained in the cell and the excess liquid flows back tothe mainstream in the channel I I.

It is particularly desirable tokeep the line 2I and other parts of thesampling and testing instrumentalities free of obstructions; to thatend, the inlet 22 is located downstream of the sewage screens I2, andmay be specially protected with further screens as indicated by thedotted lines 32. In some cases, a periodic flushing of the sample line2I-25 may be desirable in order to remove solid matter or otherobstructions lodged therein.

It will be understood that the sample removed from the channel II by thepump 22a is preferably small in relation to the extent of the mainreaches the cell.

The electrical output of the cell 30, comprising a pair of leads 33-44having a potential between them which is dependent upon the residualchlorine content of the tested sample, is connected to a sensitivetranslating device which may conveniently have recording means formaking a continuous record of the cell reading. For this purpose, arecording potentiometer, e. g. a recording millivoltmeter of thepotentiometer type, is shown in the drawings and generally designated bythe reference number 35.

Before describing the'further' connections of the instrumentalitiescontrolled by the cell 30, the means for controlling the chlorinator inaccordance with variations of flow mayconveniently be described. Thechlorinator generally designatedby the box 40 may advantageously be ofthe type illustrated in United States.Patent No. 1,777,987. issuedOctober 7, 1930, to Charles F. Wallace, for Apparatus for treatingwater, and the principal instrumentalities diagrammatically shown withinthe box 40; are identical with those appearing in the upper part, andthe extreme left hand side of the lower part, of Fig. 6 oi. the citedpatent. In view of the disclosure of the patent it will be suflicient topoint out that by means of an aspirator H a vacuum is produced in theconnected lines 42 and 43. Variations in the extent of this vacuum ornegative pressure serve to control the amount of chlorine introducedinto the pressure and whence it passes through the metering orifice 41and line 48, to be drawn into the stream traversing pipe 44 by, anaspirator or in: jector 49. These and associated instrumentalities aredescribed in the cited Wallace patent, to

which reference may be had for further explanation of the means wherebyvariations in the vacuum or negative pressure of line 43 serve tocontrol the amount of chlorine injected into the I sewage by line IS.

The vacuum control line 43 opens into the interior of a bell 50, whichhas its lower edge sealed in a pool of suitable liquid, e. g. mercury,in the lower part of acontaining vessel The vacuum chamber provided bythe bell has a lower stationary portion 52 and an outlet provided with acontrol valve 53. The valve 53 is adapted to be operated by a rod 54which extends through and in sealed connection with the top of the bell56 in such way that as the rod is pulled up, the valve 53 is broughtmore closely into its seat, and vice versa; whereby the valve is openedor closed in varying degree relative to the atmosphere, and consequentlyprovides a variation of the amount of vacuum within the bell 58 and thuswithin the lines 42 and 43. Vacuum-controlling instrumentalities of thisgeneral type are shown and described in the above cited Wallace PatentNo. 1,777,987, and also in greater detail in United States Patent No.1,762,706 to Charles F. Wallace, is-

- sued June 10. 1930, for Apparatus for producing a proportionatelyvarying negative pressure.

In order to effect vertical adjustment of the rod 54 both in accordancewith variations of flow and variations in chlorine demand per unitquantity, the following instrumentalities, shown in Fig. 2 in greaterdetail, may be provided: The float 20 is mechanically connected, asthrough rod 55, to exert force upwardly against one arm of a lever 66which is pivoted at a fixed fulcrum 6| and provided with acounter-weight 62, so that the lever itself (apart from any forceexerted by float 28) is in static balance about the pivot 6|. A similarlever 10, oppositely arranged above lever 60, is pivoted about a fixedfulcrum II and. provided with a counter-weight 12 so that it is likewisein static balance about its pivot. The rod 54 of the controlling belldevice 58 is pivotaliy connected to the longer arm of lever 16corresponding to the opposite connection of the flowmoved to the right,the upward force or rod 54 is increased, so that the valve is shiftedtoward closed position. Likewise, the effect of controlling variationsin upward force exerted by the float 20, upon the valve 53, will vary inproportion to the positional adjustments of the pivot 15. It may-beexplained that the pivot member I5 is conveniently suspended by spring18 or like means providing for a long circuit suspension,

which prevents the weight of the pivot member and its associated partsfrom exerting any force on the levers, and yet permits the pivot to bemoved freely in a horizontal, i. e. lateral direction.

It will also be understood that the sensitive valve 53 and its controlare advantageously such that very slight displacements thereof areordinarily amply sufficient for the described control, under variationof force by (rather than appreciable movement of) the float 26.

For adjustment of the pivot I5, the body of the latter is secured to alight, rigid, horizontallyextending rod or arm 19 carrying a rack 88. Apinion 8|, driven by a servo-motor 82, isin mesh with the rack 86, sothat upon rotation of the gear 8|, the rack 80, and consequently thepivot 15, are moved to the right or left, depending upon the directionof rotation of the gear 8|. It will be understood that although shown asdirectly driven, the gear 8| may, if desired, be driven from the motorby suitable reduction gearing, to provide more sensitive response incertain cases.

For control of the motor 82 in accordance with the readings of the cell30, the recording arm or like element of the meter is adapted to shift acontact arm 84 along a resistor 85, in

- accordance with the meter reading. A similar responsive rod to thelonger arm of lever 60.

A laterally displaceable pivot 15 is disposed intermediate the levers 68and 18 for transmitting force between them and conveniently includesrollers 16 and 11 respectively engaging the upper surface of lever 66between rod 55 and fulcrum 6-l and the under surface of lever 10 betweenthe rod 54 and fulcrum ll. slight vertical displacement of the float 28.occasioned by a change in the flow of sewage, will affeet a proportionalvertical displacement of the rod 54 through the systems of levers justde-' scribed, and consequent adjustment ofvalve 53 and the controllingvacuum within the bell 56.

It will also be noted that the posit on of the rod or link 54 (andconsequently valve 53) for any given position of rod 55, w ll dependupon the location of the pivot 15. For example, if the pivot 15 is movedto the left. the closing force transmitted to the rod 54 is decreased,so that the valve will open more; and if the pivot is contact arm 86 isarranged to be shifted by the assembly of rack and arm I9, along a likeresistor 81. The terminals of-resistor are conveniently connected to thecorresponding terminals of resistor 81, and a source of alternatingpotential is applied between their connecting leads 88, 89, by means ofthe leads 98. The adjustable contact arms 84, 86 are respectivelyconnected to the input terminals of a suitable amplifier unit, such as avacuum tube amplifier 92, and the amplifier is so constructed and soconnected to. the servo-motor 82 that the latter will drive theresistance arm 86 in one direction or the other, as necessary, to causethe arm 86 to follow up the displacements of arm 84.

- That is, the circuit of the resistors 85, 81, and the associatedcontact arms 84, 86, provide a bridge across the input of the amplifier;normally, the bridge circuit is in' balance and the motor 82 controlledby the amplifier does not run. If

- the bridge is unbalanced, as by displacement of It will now be seenthat s the recorder arm 84 (under control of the cell 38), the motor 82will be caused to run until its resulting adjustment of the contact arm86 restores balance in the bridge circuit, whereupon the motor stops. Atthe same time, the concomitant displacement of arm 19 by the motoreffects a lateral displacement of pivot 15 which is proportional to thecontrolling displacement of the recorder arm 84, and thus to theresidual chlorine content of the sampled sewage, as determined by thecell 30. As will be understood, the connections are such that uponincrease in residual chlorine,i. e. excess chlorine after the reactionof treatment,-the displacement of the pivot member 15 is to the left (asseen in the drawing), for decrease of the vacuum in bell 58 and decreaseof the rate of chlorination by chlorinator 40; and vice versa upondecrease of residual chlorine,the chlorination control being thusproportioned to the demand, to which the amount of residual chlorine inthe sample is inversely proportional.

For particularly efiicient resu1ts, the servomotor 82 may convenientlycomprise a shading coil motor, having a field winding (not shown)supplied from an alternating current line 95 (which through a suitabletransformer supplies alternating current to the line 90) and havingnormally opposed sets of shading coils which are connected forenergization by the amplifier to cause rotation of the motor when thereis an unbalance in the control circuit previously described.Amplifier-controlled apparatus of this general character, suitable foruse in the system here shown, is described and claimed in the copendingapplication of John R. MacKay, Serial No. 74,895, filed April 17, 1936,for Motor control apparatus. For convenience, the present drawings showcertain elements of these controlling instrumentalities, such as theamplifier and the motor, in a very simplified and diagrammatic form, andfor more detailed illustration and explanation, reference mayconveniently be had to the cited MacKay application.

It will be understood that although the described means are at presentpreferred because of their rapid response and nonhunting character,other kinds of instrumentalities may be employed for causing the pivot15 and its arm 19 to follow-up the movements of the recorder arm 84, orfor other like controls hereinafter described; indeed, in the kind ofcircuit shown,

other control means than variable resistors,-

e. g. variable inductors,may be employed, as in the manner specificallyillustrated in the cited MacKay application.

As in part already explained, residual chlorine indicating cells of thetype herein identified, and described for instance in the above citedPomeroy Patent No. 2,076,964, normally operate as follows:

operated in such way that the chlorine demand of the sample may exceedthe supp y, the reading of the cell may actually become negative, andafiord corresponding change in control as in the case of a decrease ofpositive reading.

The controlling operations, as carried out with the apparatusillustrated in Figs. 1 and 2, will now be understood to be as follows:As the sewage fiows in along the channel II, it is continuously sampledthrough the line 2| and continuously receives an application ofchlorine, at a predetermined constant extent per unit quantity, from thesmall chlorinator 23. Reaching the cell 30 at a constant head, after aperiod of time sufiicient to provide a suitable of reaction, thechlorinated sample is tested for its residual chlorine content by thecell. By means of the recorder 35', servo-motor 82 and the intermediatecontrolling instrumentalities, variations in chlorine content aretranslated into positional variations of the pivot 'l5; e. g., as theresidual chlorine content increases, indicating a decrease in demand perunit quantity, the pivot is moved to the left (as seen in Fig. 2), andas the residual chlorine content decreases, indicating an increase indemand per unit quantity, the pivot is correspondingly displaced to theright. At the same time, variations in the displacing force exertedbythe fioat 20, responsive to changes in flow of the sewage, arereceived by the conversion levers 60-10, and in consequence the valve 53is positioned in accordance with variations in rate of fiow as well asvariations in demand per unit quantity of the liquid. As previouslyexplained, variations in the position of the valve 53 varies the degreeof vacuum, or negative pressure, within the bell 50 and lines 42 and 43,so as to produce corresponding variation in the rate of feed oi chlorineto the sewage through the pipe I9.

By way of specific example, let it be assumed that the flow of sewage isat the rate of 100 gallons a minute, that there is a 3 inch head on theweir l3, and that the chlorinator is feeding at the rate of pounds per24 hours and has a metering device with a maximum capacity of pounds ofchlorine per 24 hours. In consequence of the structural arrangementshown, the vacuum differential across the chlorinator meter is 2 inchesof water, and it may be further assumed that these conditions occur whenthe recorder (under control of the cell 30) has a demand reading of on ascale graduated from zero to a maximum of 100. Let it now be assumedthat the demand reading suddenly increases to 75 on the recorder, withno change in fiow; sudden and substantial changes in chlorine demandindependent of flow, as well as rapid changes of flow more or lessindependent of chlorine demand, being characteristic of most sewagesystems.

Following the displacement of the recorder arm 84 to a value of 75, themotor 82 will be operated to efiect corresponding displacement ofresistance arm 86 for restoration of balance in the bridge circuit. Atthe same time, the motor, through the instrumentalities of rack 80 andarm 19, will have moved the pivot member 15 proportionately to theright, i. e., toward the link 54. The resulting new position of thepivot increases the leverage of the float, and to balance the latter agreater pull is required of link 54. As a result, a larger vacuum (equalto 4 /2 inches of water) is produced under the bell, and in consequencethe chlorinator increases the fiow of chlorine, i. e., to a rate of 15pounds per 24 hours. As previously explained, any change in rate of fiowof the sewage which might occur at the same time is automatically takencare of, since the vacuum across the chlorinator metering orifice isalways varied in proportion to the flow, although the control ratio maybe varied, i..e., secondarily proportioned, by displacement of the pivot15. In this connection, it will be noted that the position of the pivot15 is governed only by the chlorine demand, and corresponds definitelyto the extent by which the chlorine demand may be higher or lower, asthe case may be, than a convenient control point (correspondels from thesampling point 22 to the point of ing, say, to a reading of 50 on therecorder scale).

It will be understood that as the sewage travreaches the cell 30, theportion of sewage from which that particular sample was withdrawnreaches, in the main flow, the locality of principal chlorine injection,and since the response of the meter 35 and the adjustment of the pivotmember 15 are practically instantaneous, the chlori nator is thenactually being adjusted under the control of that sample. -In practice,with apparatus of the character illustrated, the system is ordinarilyarranged so that the sample reaches the cell 30 at a time slightly aheadof the arrival of its parent portion (in the main flow) at the localityof pipe I9; thus the chlorinator has time to adjust itself, and thecorrespondingly increased or decreased supply of chlorine will arrive inthe sewage in exactly timed relation with the actual change in demand.

As the rate of flow of the sewage changes, however, the time of itstravel between pipes 2| and I9 will also change. In many cases, thisvariation is not of great importance; for instance, where a settlingchamber I5 is employed, there r is usually considerable mixing in it,and slight discrepancies between changes of chlorine application andchanges in chlorine demand are ironed out in the settling chamber.Incertain cases, however, it may be necessary to make some adjustment ofthe speed at which the sample arrives at the cell, in accordance withsubstantial changes in the rate of flow of the main body of sewage. Suchadjustment can be obtained manually, for instance, by means of athrottling valve 91, conveniently disposed in an extension of the sampleline beyond the pipe 25 which conducts the chlorinated sample to thecell. That is, the valve 91, through its associated outlet pipe 90,by-passes some of thesample to waste, or back into the channel II,thereby slowing downthe flow in the remaining section 25 of the sampleline, it being understood that to facilitate such control, the pump 22aand chlorinator 23 may conveniently have a predetermined maximumadjustment, so that valve 91 can be opened to the extent necessary toreduce the flow in the sample line section 25 for suitablecorrespondence of the interval between sampling and testing with theinterval between sampling and actual introduction of chlorine.

.In some cases, automatic adjustment of the rate of sampling isdesirable, and to that end apparatus such as illustrated in Fig. 3 maybe employed. Certain elements and instrumentalities in Fig. 3correspond, as will be appreciated on inspection, with parts shown inFig. 1, andtfor convenience a number of parts are omitted (including therecording meter, conversion levers, chlorinator, and associatedelements), which may be assumed to be the same as in Fig. 1. In Fig. 3 asinglemotor 24a is arranged, as diagrammatically indicated, to driveboth the small capacity chlorinator 23 and the pump 22a. Under controlof a floweresponsive device, such as a supplementary float I adjacent tothe float 20, the speed of the motor 24a is varied in accordance withvariations in the rate of the sewage I0 through the channel II.

Although other means to that end may be used, a preferred arrangementincludes a pair of center-tapped inductances IOI, I02, having adjustablecores I03. I04, respectively positioned by a servo-motor I05 and thefloat I00. The centar-tapped inductances IOI, I02 are convenientlyarranged, as shown, in a bridge circuit which is adapted to be suppliedwith alternating potential from an alternating current line I 01 andwhich is connected across the input of an amplifler unit I08, in themanner specifically illustrated and described in the above cited patentapplication of John R. MacKay, Serial No. 74,895. As likewise theredisclosed, the output of the amplifier is adapted to energize theshading coils I09.of the servo-motor I 05 in accordance with positionaldifferences between the cores I03 and I04, so that the core I03 followschanges in position of the core I 04 produced by vertical displacementof the float I00. At the same time, and likewise operated by theservo-motor I05,.a speed controlling rheostat II 0 in the circuit of themotor 24a is adjusted.

Unlike the float 20, the float I 00 actually moves up or down, withvariations in the rate of flow over the weir I3, and in order tocompensate for the fact that the vertical displacements of the float I00are not linearly proportional to the variations of flow (but vary as afunction thereof which depends, as will be understood by those skilledin the art, on the specific design of the weir and the notch or the liketherein), a suitable cam H2 and follower II3 are provided in themechanical connection intermediate the motor. I05 and the movablecontact arm II4 of the rheostat H0; and in cases where adjustments ofthe rheostat and resulting speed variations of motor 24a may bear anon-linear relation, the cam II2 may also be constructed to compensatefor such further non-linearity, as well. It will therefore be seen thatvariations in flow of the liquid through the channel II will efiectcorresponding variations in the rate of fiow of the sample in the line2|, so that the desired timing between the arrival of the sample at thecell 30 and the arrival of the parent portion of the main flow at thepipe I9, is automatically maintained. At the same time, the testchlorinator 23 is correspondingly adjusted in rate, so. as to maintainthe desired constant extent of chlorination per unit quantity of thesample traversing the line 2|.

For simplicity of illustration Fig. 3 shows a series motor 24a tooperate the small chlorinator 23 and pump 22a, but it will beappreciated that if desired, other motors may be used instead, such asshunt or compound motors, which are usually more reliable and moreaccurately adjustable than the customary type of series motor.

Thus for example, a D. C. shunt motor may be substituted for motor 24a,and have the variable resistance IIO connected in series with its fieldfor accurate speed control; and if it is desired to energize such motorfrom the A. C. line I01, a rectifier can be interposed between the lineand themotor, to provide the necessary direct current. It will also beunderstood that other arrangements than those shown in Fig. 3 may beemployed to obtain automatic adjustment of the :rate of sampling. Forinstance, in Fig. 1 a supplementary float (not shown), like the floatI00 in Fig. 3, may be directly mechanically connected to adjust thevalve 91 in accordance with variations in rate of flow of the stream I0;or the valve 91 may be similarly adjusted by a servomotor (not shown)like the servo-motor I05 of Fig. 3, electrically controlled by thesupplementary float in the same way as illustrated in Fig. 3,-suchadjustment of the valve being conveniently effected through acompensating device such as the cam H2 in Fig. 3, for like compensationof non-linear control.

Although the illustrated examples are shown in connection with thechlorination of sewage at lowed by sewage disposal plants, similarapparatus may be applied for controlling post-chlorination, 1. e.,chlorination at a latter stage in the treatment, and in such case thetank in Fig. 1 may be replaced by the final settling chamber, Similarly,in either case, the weir l3 and associated float may sometimes belocated below, i. e., down-stream of, the settling chamber, although ingeneral more accurate results are obtained when the variations in floware determined at a point ahead of such chamber. point of final settlingin a sewage plant, the location of the flow-responsive device is usuallyof less importance since the most rapid variations of flow are usuallymuch ironed out by passage through previous settling tanks and filters.

Figs. 4 and 5 illustrate another arrangement of the invention, wherebythe rate of chlorine application or other treatment is automaticallyadjusted in accordance with pretested determinations of both chlorinedemand and rate of flow, of the untreated material, and wherein adifferential converter or like instrumentality, as embodied in thesystem of levers shown in Figs. 1 and 2, may be dispensed with.Referring to Figs. 4 and 5, which show the sewage channel respectivelyin elevation and plan, the sewage 2l0 to be treated advances in achannel 2 to a weir 2|3, over which it flows into a further channel 2.The weir 2I3, however, is constructed in two portions, having a majorpart 213a over which the main body of the sewage passes, and a separatedminor part 2l3b over which a minor or sample portion of the sewageflows. The channel 2 is conveniently divided by a longitudinal-partition2|4a extending, for

- example, beyond the main point of chlorine application, so as toprovide, in effect, a small parallel channel for the sample flow passingover the weir section 2 l3b, the sample being returned to the main flowat the end 2l4b of the partition. By virtue of this arrangement, thespeed of the sample 2l0a is the same as-that of the main now in thechannel 2, i. e., is automatically proportioned in rate of flow to thatof the main body of sewage.

A small capacity chlorinator 223, similar, for example, to the device 23in Figs. 1 to 3, is arranged to inject chlorine into the sample flow2l0a at the point 223a. At a place sumciently downstream to permitsuitable completion of the chlorine reaction for purposes of the testhereinafter described, liquid is withdrawn from the sample flow 210a bya sample line 22l having an inlet 222 suitably protected by screens 232in a manner similar to the sample inlet 22 of Fig. 1. A pump 222aconveniently withdraws the sample through the line 22] at a constantrate and delivers it to a constant level box 226 (similar to the box 20in Fig. 1), from which the chlorinated sample flows at a constant headinto a residual chlorine indicating cell 230, likethe cell in Fig. 1. Asthe small standard chlorinator .223 is arranged to operate at a constantrate, 1. e., to deliver chlorine to the sampling 2l0a at a constantpredetermined amount per unit of time, it will now be appreciated thatthe quantity of residual chlorine as determined by the cell 230 variesboth in accordance with variations in chlorine demand. per unit quantityof the sewage. and in accordance with variations in rate of flow oi thesewage.

- That is, if the chlorine demand, for example,

However, in effecting chlorination at the stream through the pipe 2I8.

an early stage in the procedure commonly folincreases without any changein the rate of flow, the residual chlorine detected by the cell 230 willbe less, while if the rate of flow increases (even though there may beno change in demand per unit quantity), the sample 2l0a will receiveless chlorine per unit quantity, and the residual detected by the cellwill also be less. Changes in an opposite direction will have acorrespondingly opposite effect, and simultaneous changes in bothfactors will have a conjoint efl'ect depending upon their respectiveneeds for variation of the rate of chlorination of the main stream,- e.g., if an increase in the rate of flow is accompanied by a simultaneousdecrease in the extent of chlorine demand per unit quantity in suchmutual relation that no change in the rate of principal chlorinationwould be wanted, there will be no change in the amount of residualchlorine detected by the cell 230.

The chlorination of the principal stream of sewage can be achieved witha chlorinator 240 similar to that illustrated at 40 in Fig. 1, anddispensing chlorine-containing water into the Although other controllingdevices may be used, such as the arrangement including the bell shown inFigs. 1 and 2, together with means for adjusting the valve 53 inverselyin accordance with the readings of the chlorine-sensitive cell (e. g.,by substituting a spring for the float 20 and rod 55 in Fig. 2, wherebythe valve 53 would be controlled only by member 15 under control of acell-controlled recorder 35), Fig. 5 illustrates a-somewhat differenttype of rate controller for efiecting variations oi the vacuum ornegative pressure in the line 243,the latter corresponding, as will nowbe understood, to the line 43 in Fig. 1, and similarly providing forcontrol of the rate of chlorination in accordance with variations in thecontrolling vacuum.

The illustrated rate controller 300 comprises a sealed vessel 30lpartially filled with liquid, e. g., water, and having an end of thevacuum pipe 243 opening within the container and above the surface ofthe water, A control tube 302 extends from below the surfac: of thewater and is open to the atmosphere at its upper end, and is alsoarranged for displacement vertically so as to vary the distance to whichits lower endis submerged in the water. It will now be appreciated thatthe amount of vacuum maintained in the line 243, under influence of anaspirator or like device in the chlorinator, will depend upon thesubmerged length of the control tube 302; and as the tube is adjusted,the extent of vacuum (measured in inches of water) will becorrespondingly varied.

Vertical adjustment of the control tube 302 under control of the cell230 may be readily ef-' fected; for example, in the same manner as theadjustment of the pivot 15 in Fig. 2. Thus the electrical output of thechlorine-sensitive cell 230 is connected to a recording meter 236, likethe meter 35 in Fig. 2, foradjustment of a contact arm 284 along aresistor 285 in accordance with variations of potential corresponding tovariations of residual chlorine. A servo-motor 282, having shading coils282a energizable from the output of an amplifier unit 292, is connectedto drive a gear 28l for operation of the rack 280 to displace thecontrol tube 302. As in Fig. 2, movement of the motor 282 also efi'ectsfollow-up displacement of a contact arm 286 along a resistor 281, thelatter being connected with the resistor 285 to provide a normallybalanced bridge the cell 230) drawn in proportion to the rate of flow ofthe main stream, and the sample is subjected to a standard testchlorination at a predetermined fixed rate (preferably slightly abovemaximum possible demand), i. e., at a fixed extent per unit of time, sothat the quantity of liquid receiving a given quantity of chlorine willnaturally vary in proportion to variations of flow. The sample thuschlorinated is then allowed suflicient time to bring the reaction to adesired point of completion, whereupon it is tested for residualchlorine content per unit quantity, and the rate of application ofchlorine to the main stream of liquid is then controlled inversely inaccordance with the residual chlorine content thus determined. Thecontrol of the chlorinator by the cell is thus similar to the controlexerted by the cell 30 in Figs. 1 and'2 (i. e., inversely in accordancewith the quantity of residual chlorine) but instead of being related,only to the demand per unit quantity, it automatically includes suchmodification ascis necessary to account for changes in rate of flow.

It will be understood that the point of application of chlorine throughpipe M9 to the main flow is positioned somewhat down-stream of theposition of the test sample inlet 222,-thus affording time not only forthe desired completion of reaction of the test chlorine application inthe sample, but also for the controlling operations within thechlorinator (under the practically instantaneous control of the ratecontroller 300 by Inasmuch as the sample 2l0a is travelling at the samespeed in the sample channel as the main body of liquid in the major partof channel 2, there is ordinarily no need for supplementary timingcontrol such as provided by the valve 91 in Fig. 1 or by the instrumentalities shown in Fig. 3; it being understood that the spacing of pipes223a and 222 is preferably sufiicient to allow for the desiredcompletion of reaction even when the flow is at a maximum rate.

F In some cases, the control operations described in connection withFig. 5 may be attained with other devices. For example, other means maybe employed to provide sampling in proportion to the rate of flow; thusfor instance, the sample may be withdrawn through a pipe by a pumphaving its speed controlled in proportion to the rate of flow of themain stream, as 'in the manner of the motor 24a and pump 22a in Fig. 3,it being understood. that in such case therate of the small capacitychlorinator is not correspondingly varied, but remains at apredetermined constant rate, like the chlorinator 223 of Fig. 5 and forlike reasons. It will also be appreciated that in some instances or forsome purposes, the invention may be carried out with apparatus differingin a variety of other respects from the specific devices hereinabovedescribed. For instance, 'in Figs. 1 and 2 the differential converterembodying the levers 60 and I0 may be dispensed with and the jointcontrol of the vacuum in the chlorinator tube 43 by variations of cellvoltage and variations of a flow-responsive device, may be efiected by amore completely electrical system,for example, a system of the typesdescribed and claimed in the copending application of John R. MacKay,Serial No. 244,054, filed December 5, 1938, for Proportional controlsystems and procedure, and particularly control means ofthe sortincluded in Figs. 13 and 14 of 1 said application, which illustratearrangements for controlling a chlorinator jointly in accordance withdeterminations of a chlorine-sensitive cell and a flow-responsivedevice.

While illustrated in connection with sewage treatment systems andalthough being of special advantage for such systems, the procedure andapparatus of the invention may be applied toother uses. One such use isin the treatment of water for drinking purposes, as in such cases thechanges in the demand for chlorination may also be quite rapid,particularly for certain types of water supply systems. In such case,the liquid is preferably handled in a closed conduit, rather than anopen channeLand a Venturi-tube with an associated differential converterof the general type and hydraulic system shown in Wallace Patent No.1,762,706 may be equipped with a motor-controlled laterally-shiftablefulcrum and conveniently used in lieu of the weir and associated floatas shown in Figs. 1 and 2. Conventional Venturi meters :may also beconnected, like the float 20, to control a differential converter of thetype shown in Figs. land 2 or to operate other control means ashereinabove described. Arrangements of the sort exemplified in Figs. 4and 5 may also be applied for use in water purification, and in suchcase the sample stream can be drawn from the main conduit by a pumphaving its speed controlled by a Venturi meter in the main, to providethe desired sampling proportional to the main flow.

In some cases, other types of chlorinators than those controlled by achange of vacuum may be employed, and other feeding or treating devicescan be subjected to the same sort of control e. g., dry chemical feedersor other feed apparatus for liquid, solids or gases; the control beingin accordance with demand as detected, say from the condition of asample subjected to a test treatment, which may be of the same characteras the principal treatment, or of a different character peculiarlysuited for detecting demand. For instance, in a water works wherecoagulating chemicals are applied ahead of a filter or settling basin,the procedure of this invention may be effectively employed, bysubstituting a standard test feed of the chemical for the illustratedsmall capacity chlorinator and substituting a photoelectric cell andinspecting device therefor, for the chlorine-sensitive cell,so thatthe'feed of coagulating chemical is controlled inresponse to detectedvariations in turbidity'or color of the sampled material. In othercases, for controlling chlorination, the chlorine-sensitive cell maylikewise be replaced by photo-electric means and arrangements providedfor producing a color reaction in the test-treated sampling of material(e. g., by using ortho-tolidin) to develop a color in accordance withthe residual chlorine content, whereby the determination of colorvariations by the photo-electric device is utilized to control the rateof chlorine feed.

It will now be seen that the present invention aflords a notablyaccurate and non-hunting control of the treatment of a flowing materialin accordance with its actual demand per unit quantity, and is ofspecial and distinct advantage in apparatus and procedures where boththe'flow variations and the demand changes in the material to betreated, are frequent and substantial. If desired, a second'andindependent indicating or recording device can be located down-stream ofthe point of principal treatment, to indicate or record the result ofthe latter,-whereby a record or other check of the operation will beafforded.

In accordance with the provisions of the patent statutes, I have hereindescribed the principle of operation of my invention, together with theprocedure and apparatus which I now consider to represent the mostadvantageous embodiments thereof, but I desire to have it understoodthat the apparatus disclosed is only illustrative and that the inventioncan be carried out by other means. Also, while it is designed-to use thevarious features and elements in the combinations and relationsdescribed, some of these may be altered and others omitted and some ofthe features of each modification may be embodied in the others withoutinterfering with the more general results outlined, and the inventionextends to such use within the scope of 'the appended claims.

I claim:

1. A method of controlling the treatment of a flowing material,comprising subjecting the material to a principal treatment, detectingchanges in demand by subjecting a portion of the untreated material to asimilar test treatment which modifies the condition of the material in adetectable manner and detecting variations in the condition of theresulting treated portion relative to a predetermined standard, andvarying the principal treatment of the material in response to saidvariations in condition, to cause said principal treatment to follow thedetected changes in demand.

rate of treatment in accordance with the detected variations; saiddemand variation detecting step including subjecting successive portionsof the untreated material, at a place upstream of the place oftreatment, to a test which is responsive to variations in demand of thesuccessive portions for treatment per unit quantity, while convertingvariations in rate of flow of the material into modifications of theresult of said test, to determine the aforesaid variations in demand perunit of time, for control of the rate of treatment, and

said subjection of portions of the untreated material to a test,comprising subjecting said portions to a treatment of controlled extent,similar to the main treatment, and testing the treated portions todetect the results of the treatment hereof. 3. In apparatus of thecharacter described, the combination, with a chlorinator for treating aa flowing material, of a treating substance which requires a substantialperiod of time to complete its desired treating effect on the material,and which modifies the condition of the material in a detectable manneradapted to vary with the amount of substance applied, comprisingdetecting the rate of demand of the flowing material for treatment, inaccordance with both its rate of flow and its demand per unit quantity,said rate-detecting step including effecting a standard test applicationof the treating substance to a portion of the material and aftercompletion of the treating effect on said portion, detecting variationsin the condition of the treated portion from the desired treatingeffect; effecting the vice whereby said chlorinator may be controlled,

of means for withdrawing a sample flow of saidprincipal application-ofthe treating substance to the material at a place downstream of thatwhere the aforesaid portion is subjected to test application; andvarying the rate of said principal substance application in accordancewith detected variations in rate of demand for treatment whilecorrelating and timing the said rate-detecting procedure with control ofthe rate of substance application to effect substantial coincidence ofactual variation in substance application with the arrival of thecontrolling variation in the material at the point of said application.

5. A method of controlling chlorination of a flow of aqueous liquid,comprising sampling the liquid at a place upstream of the place of thechlorination to be controlled, chlorinating said sampling of liquid at acontrolled rate, testing said chlorinated sampling to determine residualchlorine, and varying the rate of the first-mentioned chlorinationinversely in accordance with the determined amount of residual chlorine.

6. The method of claim 5 which includes timing the testing step relativeto the sampling step and in accordance with the rate of flow of theliquid, to effect substantial coincidence of the controlled variation ofchlorination with the arrival, at the place of chlorination, of thevariation in liquid condition which effects the correspondingcontrolling determination of residual chlorine.

7. Apparatus adapted for use in controlling the treatmentof flowingmaterial, comprising means for withdrawing successive sample portions ofthe untreated material, means for testing the sample portions withdrawnby said first mentioned means to detect variationsin demand ofthe'material for treatment per unit quantity, means for detectingvariations in the rate of flow of the flowing material, an adjustabletranslating device, and means responsive to both said testing means andsaid detecting means, for adjusting said translating device inaccordance with the demand of the material for treatment per unit oftime.

8. A method of controlling chlorination of a flowing aqueous liquid,comprising sampling the liquid before chlorination thereof, treatingsuccessive sampled portions to introduce a controlled quantity ofchlorine therein, testing said successive portions after treatment todetect differences in the effect of said introduction of chlorinetherein, subjecting the main body of flowing liquid to chlorinationtreatment, and converting detected differences in the effect oftreatment of the sampled portions into changes in chlorination treatmentof the main body of liquid, to maintain desired uniformity of the eifectof said chlorination treatment on said main body of liquid.

9. The method of claim 8, wherein the sampling and treating stepsinclude varying the rate of sampling in accordance with variations ofthe rate of flow of the main body of liquid, while maintaining thechlorine-introducing treatment of the sampled portions at a constantrate, whereby the detected difierences of effect of said introductionreflect variations in rate of flow of the main body of liquid.

10. Apparatus adapted for use in controlling the treatment of flowingmaterial, comprisingmaterial-handling means for sampling the material ata rate varying with variations of the rate of flow of the material,means for applying treatment at a predetermined constant rate to thesample of material handled by the first-mentioned means, means fordetecting variations in the condition of the treated sampling from adesired result of treatment, an adjustable translating device, and meansresponsive to said detecting means for adjusting the translating device,to control the latter in accordance with variations of both rate of flowand demand for treatment per unit quantity, of the flowing material.

11. In apparatus of the character described,

I provided supplementary means for detecting,

variations in rate of flow of the material to be treated, and whereinthe control-operating means includes associated means responsive to theaforesaid supplementary means, for operating the control means inaccordance with changes in rate of flow.

13. The apparatus of claim 11, wherein the sampling means includes meansregulating the sampling in accordance with the rate of flow of thematerial to be treated, and wherein the treatment-applying means isadapted to treat the sample at a constant rate regardless ofquantitative variations of the sampling, whereby the changes incondition detected by the detecting means are governed both by changesin rate of flow and by changes in demand for treatment per unitquantity.

14. Apparatus for controlling the rate of a chlorinator for a flowingliquid, comprising a chlorinator for said flowing liquid, means forchlorinating a sample of the liquid untreated by said chlorinator, meansfor testing the chlorinated sample for residual chlorine, and controlmeans responsive to said testing means and adapted to vary the rate ofthe chlorinator inversely in accordance with the determination of saidtesting means.

15. In combination, liquid-handling means, a chlorinator for treating aliquid which flows in said handling means, means for withdrawing asample of said liquid from said handling means,

upstream of the chlorinator, means for treating the sample withchlorination of predetermined character, electrolytic cell means fordetermining residual chlorine in the treated sample, and meanscontrolled by the cell means for control-- ling the chlorinatorinversely in accordance with the determination of said cell means.

16. In combination, means for handling'a flow of liquid, means forsampling liquid therefrom, means for chlorinating the sample at aconstant extent per unit quantity, means for detecting residual chlorinecontent of the chlorinated sample, means for detecting variations inrate of flow of the liquid, and means controlled by both said detectingmeans for effecting chlorination of the liquid at a rate varying inaccordance with the rate of flow and inversely in accordance with theresidual chlorine content of the treated sample. i

17. In combination, means for handling a flow of liquid, means forsampling liquid therefrom in proportion to the rate of flow of saidliquid, means for chlorinatlng the sample at a constant rate whereby thequantityof chlorine applied per unit quantity varies inversely inaccordance with the rate of flow of the liquid, means for detectingresidual chlorine content of the chlorinated sample, and meanscontrolled by said detecting means for eifecting chlorination of theliquid at a rate varyinginversely in accordance with the residualchlorine content of the treated sample.

18. In combination, a vacuum-controlled chlorinator for applyingchlorine to aflow of liquid, positionally adjustable means for varying avacuum to control the rate of the chlorinator, means for applying'chlorine to untreated portions of the liquid to be chlorinated, at apredetermined extent per unit quantity, means for electrolyticallydetecting variations in potential of the portions of liquid treated bysaid lastmentioned means, control means mechanically responsive tovariations in the rate of flow of the liquid to be chlorinated, a leverdevice having an arm connected to said positionally adjustablevacuum-varying means, an adjacent lever device having an arm connectedtosaid flow-responsive control means, pivot means intermediate saidlever-devices for transmitting control from the flow-responsive means tothe vacuum-varying means, and means controlled by the electrolytic meansfor positionally adjusting the pivot means to eil'ect control of thevacuum-varying means in response to the detected variations ofpotential.

19. The combination of claim 18 in which the means for applying chlorineto untreated portions of liquid comprises means including a conduit forwithdrawing a sample flow of the liquid, a chlorinator device forinjecting chlorine into said conduit at a constant extent per unitquantity of the sample, means for delivering chlorinated liquid fromsaid conduit to the electrolytic detecting means, and overflow means insaid conduit beyond the point of injection of chlorine, including avalve adjustable to vary the time interval between withdrawal of asample portion of liquid and test of the sample by the electrolyticdetecting means.

20. The combination of claim 18 in which the means for applying chlorineto untreated portions of the liquid comprises a conduit for receiving asample flow of the liquid, a chlorinator device for injecting chlorineinto the sample flow in said conduit, a pump for advancing the sampleflow in the conduit, means for conjointly adjustthe speed of the pump,and flow-responsive means for control of said adjusting means, "to '7effect operation of the latter in accordance with variations in flow ofthe main body of liquid.

21. In combination, a vacuum-controlled chlorinator for applyingchlorine to a flow of liquid, adjustable means for varying a vacuum tocontrol the rate of the chlorinator, means for handling the flow of theliquid to be chlorinated, including divided weir means for separatingfrom the main flow of liquid a sample flow having a rate varying inaccordance with variations of the main fiow and conduit means forcarrying said sample flow, means for applying chlorine to said sampleflow at a constant rate, means for electrolytically detecting variationsin potential of the sample flow after application of chlorine by thelast-mentioned'means, and means controlled by said electrolytic meansfor adjusting the vacuum-varying means in response to the detectedvariations of potential.

22. In combination, liquid-handling means, a

chlorinator for treating a liquid which flows in said handling means,means for withdrawing a sample of said liquid from said handling meansupstream of the chlorinator, means for treating the sample withchlorination of predetermined character, electrolytic cell means fordetermining the potential of the treated sample, and

means controlled by the cell means for controlling the chlorinatorinversely in accordance with the determination of said cell means.

23. A method of controlling chlorination of a flow of aqueous liquid,comprising sampling the liquid ata place upstream of the place of thechlorination to be controlled, chlorinating said sampling of liquid at acontrolled r'ate, testing said chlorinated sampling to determine itspotential, and varying the rate of the first-mentioned. chlorinationinversely in accordance with the determined potential.

DAVID CRAMPTON.

:Pgtent to. 2,269,595-

CERTIFICATE 'OF coRREc IoN. a

January 6, 1914.2;

DAVID CRAIIP'ION.

It is hereby certified that error appears in the printed specificationfor the above numbered patent requiring correction as rollows: Pagel,first eblum'n, line 16, for "desired" read --desc-ri bed-- page 5,second oolujnn,

line 1, for."or" read --on-; page. 11;, first colmnn line 6b.,strike outof; page 6, first column, line 'l 'for "latter" read 1a.ter--; page 8;,

first column, line 70, "cla imizy rfor"'hereof" read '--thereof--.; page9,'-

firstrolmnn, line 52, claim 11, for "of" read-w dth; and that'the skid-Lat'ters Patent sl buldbe read with this correction therein thatths same lma conform to -the record. of the case in the. Patent. OfficerSigned and sealed this 17th day of Harch,"A. D. 1911.2;-

Henry Van Arsdale,

Acting 'Cdnqmissioner 9f Patents.

